I-79: Appears in the April 1958 CTB Minutes as the interstate route number from "the West Virginia Line to the North Carolina Line conforming generally to a projection between Canton, Ohio and Charlotte, North Carolina as will be determined by studies already in progress."
This section was added to the Interstate plan in October 1957. By June 1958 this was renumbered as I-77.
Thanks to NE2 for the timeline for changes to I-79.